This invention relates generally to the transmission of power. More particularly it relates to rotary drive apparatus which is hermetically sealed, which compensates for appreciable shaft misalignment, and which is particularly useful in a generally inaccessable environment.
In submersible pump applications the motor shaft seal is a frequent source of failure. Face seals are sensitive to installation procedures, shaft runout, vibration and other factors which are often difficult to control. A submersible pump is inaccessable, and seal failure cannot easily be detected or repaired. Usually this leads to catastrophic failure of an entire unit. In such an application it would be desirable to have some mechanism transmitting shaft power through an impermeable, hermetically sealed stationary barrier. Other applications in which such a mechanism would be advantageous include, for example, nuclear pumps and systems incorporating freon.
It is known to provide harmonic drive devices for the transmission of power. A disadvantage of using known harmonic drive devices is that the flexible tube or so-called flex-spline must withstand a torque which is equal to the output torque. This is a particular problem in that speed reduction is involved.
There remains a need in the art for hermetically sealed rotary drive apparatus which provides positive, nonslip drive, which compensates for shaft misalignment, which incorporates a hermetic barrier, which does not experience a torque reaction other than that developed by friction torque, which is simple and easy to manufacture, install and operate, and which need not require a speed reduction.